Owners and operators of wellheads, chemical plants or similar facilities which use externally threaded metal pipes or tubing have found that frequent replacement of corroded or damaged metal pipe or tubing sections may involve the expenditure of large amounts of money. To reduce this expenditure, owners of such externally threaded metal pipe or tubing sections have found that money may be saved by protecting the exposed metal on the inside diameter of the metal pipe or tubing section with fiberglass resin liners having a concrete mortar backing. Money savings are a direct result of the significantly longer service life of fiberglass resin lined metal tubing having a concrete mortar backing. In addition, even further savings may be obtained by reworking used pipe or tubing sections so that these used externally threaded pipe or tubing sections can be put back into service by including a fiberglass resin liner with a concrete mortar backing.
While fiberglass resin liners have proven to be effective in both increasing the service life of externally threaded metal pipe or tubing sections and providing a way to put used externally threaded pipe or tubing sections back into service, there remains a need to assure that the full bore of externally threaded fiberglass lined metal pipe or tubing sections are protected when joined together within an internally threaded coupling. Such full bore connection of the externally threaded fiberglass lined metal pipe or tubing sections does several things. First, it prevents contact between fluids which both corrode and erode exposed metal surfaces on the ends of the externally threaded lined metal pipe or tubing sections and the exposed metal surfaces within the internally threaded coupling. Second, such full bore connection of the fiberglass resin liners prevents damage to the ends of the individual resin liners in each externally threaded pipe or tubing section. Third, such full bore connection provides an internal surface which will not induce patterns of turbulence into the flowing fluid.
There is therefore a need in the art to provide a reusable coupling assembly that will provide a full bore connection between two resin liners within externally threaded fiberglass resin lined metal pipe or tubing sections which are joined together within an internally threaded coupling.